The invention relates to marine drives, and more particularly to a combination drive sleeve adapter and shock absorbing drive sleeve assembly mounting the propeller to the propeller shaft. The present invention evolved during continuing development and testing efforts directed toward providing a shock absorbing drive sleeve for protecting the propeller shaft and the marine drive when the propeller strikes an object. The present invention comprises a drive sleeve adapter and a shock absorbing drive sleeve assembly wherein the shock absorbing drive sleeve provides both shock absorption and high load capability. The shock absorption allows the propeller shaft to continue rotating through a limited angle after the propeller has been stopped by an object, and the high load capability supports enough torque to propel the boat through water, even under high load conditions. The drive sleeve adapter couples the shock absorbing drive sleeve to the propeller shaft.
The allowed parent applications disclose a onepiece shock absorbing drive sleeve composed of plastic, and although the plastic chosen provides sufficient product life, it was found during continued development and testing that a metal splined insert coupling the splined propeller shaft to the shock absorbing drive sleeve offered even greater service life by extending the metal-to-plastic lever arm outward. That is, the metal-to-plastic lever arm in the parent applications was at the splined propeller shaft/drive sleeve engagement area; whereas in the present embodiment, the metal-to-plastic lever arm is radially extended outward at the adapter/drive sleeve engagement area. Moving the lever arm radially outward reduces the force necessary, at that engagement area, to achieve the same torque as that at the radially inward engagement area. Therefore, extending the splines of the plastic shock absorbing drive sleeve radially outward results in increased drive sleeve spline life. The drive sleeve adapter may be a separate drive sleeve insert, or molded directly into the shock absorbing drive sleeve, or, as in the preferred embodiment, be a separate insert incorporating the rear thrust hub.